Methods of preparing tertiary alkyl primary amines, such as meta- or para-isopropenyl-alpha,alpha-dimethylbenzyl amine are disclosed in European Patent Application 127,802. One method describes hydrolyzing the corresponding meta- or para-isomer of isopropenyl-alpha,alpha-dimethylbenzylisocyanate in the presence of a strong acid, such as hydrochloric acid or sulfuric acid, to form isopropenyl-alpha,alpha-dimethylbenzyl amine hydrochloride, followed by reaction of the amine salt with a stoichiometric excess of sodium hydroxide to form the meta- or para-isopropenyl-alpha,alpha-dimethylbenzyl amine. Alternatively, a second method describes heating a solution of meta-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate in methanol to form methyl N-(3-isopropenyl-alpha,alpha-dimethylbenzyl)carbamate (hereinafter referred to as TMU), mixing the solution containing the TMU with potassium hydroxide (hereinafter referred to as KOH) at a molar ratio of TMU:KOH of from about 0.25 to about 0.5 and in a sufficient amount of 2-methoxyethanol to form a second solution, heating the second solution to convert the TMU to meta-isopropenyl-alpha,alpha-dimethylbenzyl amine, and recovering the amine from the second solution.
A major drawback of the processes in the European Patent Application is the use of strong acids and bases, which can require neutralization and result in greater waste disposal problems.
An alternative method developed to avoid the use of such strong acids and bases is disclosed in co-pending U.S. application Ser. No. 07/187,788, entitled ACRYLIC POLYMERS, by Kania et al., filed on the same date herewith. Such an alternative method involves reaction of an alcohol, such as diacetone alcohol, with a tertiary alkyl primary amine, such as meta-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate, in the presence of a catalyst to form a urethane reaction product, followed by heating for time and at temperatures sufficient to decompose the urethane reaction product and produce the meta-isopropenyl-alpha,alpha-dimethylbenzyl amine. While this method eliminates the use of any strong acids or bases, the yield of this process has been low, generally up to about 50 percent depending upon the choice of alcohol and catalyst.